In a long-term evolution (LTE) system, power control methods when terminal equipment transmits a physical uplink share channel (PUSCH), a physical uplink control channel (PUCCH), an uplink sounding reference signal (SRS) and a physical random access channel (PRACH) are defined (3GPP TS 36.213 v 8.6.0), wherein,
a formula of power control of the PUSCH is:PPUSCH(i)=min{PMAX,10 log10(MPUSCH(i))+PO_PUSCH(j)+α(j)·PL+ΔTF(i)+f(i)}[dBm]  (1);
a formula of power control of the PUCCH is:PPUCCH(i)=min{PMAX,P0_PUCCH+PL+h(nCQI,nHARQ)+ΔF_PUCCH(F)+g(i)}[dBm]  (2);
a formula of power control of the SRS is:PSRS(i)=min{PMAX,PSRS_OFFSET+10 log10(MSRS)PO_PUSCH(j)+α·PL+f(i)}[dBm]  (3); and
a formula of power control of the PRACH is:PPRACH=min{PCMAX,c(i),PREAMBLE_RECEIVED_TARGET_POWER+PLc}[dBm]  (4).
In the LTE system, the same terminal equipment does not transmit a PUSCH, a PUCCH and a PRACH in the same subframe at the same time. Meanwhile, the same terminal equipment does not transmit an SRS and a PUSCH, an SRS and a PUCCH, and an SRS and a PRACH, in the same orthogonal frequency division multiplexing (OFDM) symbol at the same time. And on the other hand, it can be seen from the formulae of power control of the PUSCH, PUCCH, PRACH and SRS that if the transmission power of the uplink signals exceeds the configured maximum output power (PCMAX) of the terminal equipment, that is, overflow of the output power of the terminal equipment occurs, the transmission power of the terminal equipment used in transmitting the uplink signals will be equal to the configured maximum output power (PCMAX) of the terminal equipment.
In Rel-10 of an LTE-Advanced (LTE-A) system, a carrier aggregation technology is used, and transmission power of uplink signals is independently controlled in each serving cell, with the power control methods being as follows:
power control of a PUSCH:
when only PUSCHs are transmitted in a serving cell c, the transmission power of the PUSCHs of the terminal equipment in an i-th subframe in the serving cell c is:
                                          P                          PUSCH              ,              c                                ⁡                      (            i            )                          =                  min          ⁢                                    {                                                                                                                                            P                                                      CMAX                            ,                            c                                                                          ⁡                                                  (                          i                          )                                                                    ,                                                                                                                                                                                                                                              10                              ⁢                                                                                                log                                  10                                                                ⁡                                                                  (                                                                                                            M                                                                              PUSCH                                        ,                                        c                                                                                                              ⁡                                                                          (                                      i                                      )                                                                                                        )                                                                                                                      +                                                                                          P                                                                  O_PUSCH                                  ,                                  c                                                                                            ⁢                                                              (                                j                                )                                                                                      +                                                                                                                                                                                                                                                                            α                                  c                                                                ⁡                                                                  (                                  j                                  )                                                                                            ·                                                              PL                                c                                                                                      +                                                                                          Δ                                                                  TF                                  ,                                  c                                                                                            ⁡                                                              (                                i                                )                                                                                      +                                                                                          f                                c                                                            ⁡                                                              (                                i                                )                                                                                                                                                                                                                    }                        ⁡                          [              dBM              ]                                                          (        5        )            
when PUSCHs and PUCCHs are transmitted in the serving cell c, the transmission power of the PUSCHs of the terminal equipment in the i-th subframe in the serving cell c is:
                                          P                          PUSCH              ,              c                                ⁡                      (            i            )                          =                  min          ⁢                                    {                                                                                                                  10                        ⁢                                                                              log                            10                                                    ⁡                                                      (                                                                                                                                                                P                                    ^                                                                                                        CMAX                                    ,                                    c                                                                                                  ⁡                                                                  (                                  i                                  )                                                                                            -                                                                                                                                    P                                    ^                                                                    PUCCH                                                                ⁡                                                                  (                                  i                                  )                                                                                                                      )                                                                                              ,                                                                                                                                                                                                                                              10                              ⁢                                                                                                log                                  10                                                                ⁡                                                                  (                                                                                                            M                                                                              PUSCH                                        ,                                        c                                                                                                              ⁡                                                                          (                                      i                                      )                                                                                                        )                                                                                                                      +                                                                                          P                                                                  O_PUSCH                                  ,                                  c                                                                                            ⁡                                                              (                                j                                )                                                                                      +                                                                                                                                                                                                                                                                            α                                  c                                                                ⁡                                                                  (                                  j                                  )                                                                                            ·                                                              PL                                c                                                                                      +                                                                                          Δ                                                                  TF                                  ,                                  c                                                                                            ⁡                                                              (                                i                                )                                                                                      +                                                                                          f                                c                                                            ⁡                                                              (                                i                                )                                                                                                                                                                                                                    }                        ⁡                          [              dBm              ]                                                          (        6        )            
power control of a PUCCH:
when PUCCHs are transmitted in the serving cell c, the transmission power of the PUCCHs of the terminal equipment in the i-th subframe in the serving cell c is:
                                          P            PUCCH                    ⁡                      (            i            )                          =                  min          ⁢                                    {                                                                                                                                            P                                                      CMAX                            ,                            c                                                                          ⁡                                                  (                          i                          )                                                                    ,                                                                                                                                                                                                                                              P                                                              0                                ⁢                                                                  _                                  ⁢                                  PUCCH                                                                                                                      +                                                          PL                              c                                                        +                                                          h                              ⁢                                                              (                                                                                                      n                                    CQI                                                                    ,                                                                      n                                    HARQ                                                                    ,                                                                      n                                    SR                                                                                                  )                                                                                      +                                                                                                                                                                                                                                          Δ                                F_PUCCH                                                            ⁡                                                              (                                F                                )                                                                                      +                                                                                          Δ                                                                  T                                  ×                                  D                                                                                            ⁡                                                              (                                                                  F                                  ′                                                                )                                                                                      +                                                          g                              ⁡                                                              (                                i                                )                                                                                                                                                                                                                    }                        ⁡                          [              dBm              ]                                                          (        7        )            
power control of an SRS:
when SRSs are transmitted in the serving cell c, the transmission power of the SRSs of the terminal equipment in the i-th subframe in the serving cell c is:PSRS,c(i)=min{PCMAX,c(i),PSRS_OFFSET,c(m)+10 log10(MSRS,c)+PO_PUSCH,c+αc(j)·PLc+fc(i)}[dBm]  (8)
The method for controlling transmission power of a PRACH is the same as that of the LTE system, which are omitted herein.
As a carrier aggregation technology is used, when the terminal equipment is configured with multiple serving cells, there will appear in the same subframe, and multiple PUSCHs are transmitted at the same time (as shown in FIG. 1(a)), or PUSCHs and PUCCHs are transmitted at the same time (as shown in FIG. 1(b)), in different serving cells. And on the other hand, as the capability of the terminal equipment is enhanced, the terminal equipment is able to transmit PUSCHs and PUCCHs in the same subframe in a primary serving cell at the same time (as shown in FIG. 1(c)).
If the above case occurs, that is, the terminal equipment needs to transmit multiple PUSCHs, or the terminal equipment needs to transmit PUSCHs and PUCCHs, in the same subframe at the same time, a case will occur where the sum of transmission power of multiple PUSCHs is greater than the configured maximum output power of the terminal equipment, or the sum of transmission power of the PUSCHs and PUCCHs is greater than the configured maximum output power of the terminal equipment. In order to direct allocation of the transmission power of the terminal equipment in such a case, a power control method in case of transmission power of terminal equipment being limited is defined in standardization of the LTE-A system. In which,
when multiple PUSCHs with no uplink control information (UCI) only need to be transmitted at the same time, the terminal equipment calculates first the transmission power needed by PUSCHs in each serving cell according to formula (5); and if the total transmission power obtained at this moment exceeds the maximum output power of the terminal equipment, the terminal equipment decreases the transmission power of each PUSCH by equivalent share, until that the total transmission power is less than or equal to the maximum output power of the terminal equipment is ensured;
when PUSCHs with no UCI and PUCCHs need to be transmitted at the same time, the terminal equipment calculates first the transmission power needed by the PUSCHs in a serving cell where only PUSCHs are transmitted according to formula (5), and calculates the transmission power needed by the PUSCHs and the PUCCHs in a serving cell where PUSCHs and PUCCHs are transmitted at the same time according to formulae (6) and (7); and if the total transmission power obtained at this moment exceeds the maximum output power of the terminal equipment, the terminal equipment first ensures that the transmission power of the PUCCHs is satisfied, and then decreases the transmission power in each PUSCH with no UCI by equivalent share, until that the total transmission power is less than or equal to the maximum output power of the terminal equipment is ensured;
when PUSCHs with no UCI and PUSCHs with UCI need to be transmitted at the same time, the terminal equipment calculates first the transmission power needed by the PUSCHs in each serving cell according to formula (5); and if the total transmission power obtained at this moment exceeds the maximum output power of the terminal equipment, the terminal equipment first ensures that the transmission power of the PUSCHs with UCI is satisfied, and then decreases the transmission power in each PUSCH with no UCI by equivalent share, until that the total transmission power is less than or equal to the maximum output power of the terminal equipment is ensured;
when PUCCHs, PUSCHs with no UCI and PUSCHs with UCI need to be transmitted at the same time, the terminal equipment calculates first the transmission power needed by the PUSCHs in a serving cell where only PUSCHs are transmitted according to formula (5), and calculates the transmission power needed by the PUSCHs and the PUCCHs in a serving cell where PUSCHs and PUCCHs are transmitted at the same time according to formulae (6) and (7); and if the total transmission power obtained at this moment exceeds the maximum output power of the terminal equipment, the terminal equipment first ensures that the transmission power of the PUCCHs is satisfied and secondly ensures that the transmission power of the PUSCHs with UCI is satisfied, and then decreases the transmission power in each PUSCH with no UCI by equivalent share, until that the total transmission power is less than or equal to the maximum output power of the terminal equipment is ensured.
In Rel-10 of the LTE-A system, when a terminal is configured with multiple serving cells, the terminal equipment uses the same uplink time advance value in transmitting uplink signals in all the serving cells, so as to ensure uplink synchronization. An initial value of the time advance is obtained by performing random access in a primary serving cell. Hence, in Rel-10, a base station configures a PRACH channel for the terminal equipment only in the primary serving cell (PCell), and the terminal equipment transmits PRACH signals only in the PCell. And at the same time, when the terminal equipment needs to transmit PRACH signals in the PCell, the terminal equipment does not transmit other uplink signals, including a PUSCH, a PUCCH and an SRS, in the PCell or other secondary serving cells (SCells).
In the implementation of the present invention, the inventors found that in Rel-11, as an uplink needs to support aggregation of carriers from different stations and an inter-band carrier aggregation technology, it cannot be ensured that all the SCells have uplink signal time advance value same as that of a PCell. In order to obtain time advance value in some SCells, the terminal equipment needs to perform random access in the SCells. Therefore, in Rel-11, the base station needs to configure PRACH channel in some SCells for the terminal equipment. And the terminal equipment also needs to transmit PRACH signals in the SCells. At this moment, besides the case occurring in Rel-10 where the terminal equipment needs to transmit multiple PUSCHs in the same subframe at the same time or the terminal equipment needs to transmit PUSCHs and PUCCHs in the same subframe at the same time, the terminal equipment may need to transmit PUSCHs and PRACHs at the same time, transmit PUCCHs and PRACHs at the same time, and transmit SRSs and PRACHs at the same time. Therefore, the occurrence of the following three scenarios will also lead to occurrence of a case where the sum of the transmission power of the terminal equipment is greater than the configured maximum output power of the terminal equipment:
scenario 1 (as shown in FIG. 2): the sum of the transmission power of the terminal equipment in transmitting PUXCHs (PUXCH refers to a PUSCH or a PUCCH) and PRACHs respectively in a PCell and a SCell at the same time is greater than the configured maximum output power of the terminal equipment;
scenario 2 (as shown in FIG. 3): the sum of the transmission power of the terminal equipment in transmitting SRSs and PRACHs respectively at the same time in a PCell and a SCell is greater than the configured maximum output power of the terminal equipment; and
scenario 3 (as shown in FIG. 4): both of the sum of the transmission power of the terminal equipment in transmitting PUXCHs and PRACHs and the sum of the transmission power of the terminal equipment in transmitting SRSs and PRACHs respectively in a PCell and a SCell at the same time are greater than the configured maximum output power of the terminal equipment.
It can be seen that when the sum of the transmission power of the terminal equipment in transmitting PUSCHs and PRACHs in the same subframe at the same time is greater than the configured maximum output power of the terminal equipment, or the sum of the transmission power of the terminal equipment in transmitting PUCCHs and PRACHs in the same subframe at the same time is greater than the configured maximum output power of the terminal equipment, or the sum of the transmission power of the terminal equipment in transmitting SRSs and PRACHs in the same OFDM symbol at the same time is greater than the configured maximum output power of the terminal equipment, how to control the power in uplink transmission of signals by the terminal equipment is an urgent problem needing to be solved at the present.
It should be noted that the above description of the background art is merely provided for clear and complete explanation of the present invention and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background art of the present invention.